All enclaves in the world have limited sovereignty, as a result of dependence on a neighboring country that is much stronger. However, in order to gain full independence, small states are often being established on different islands.
Unfortunately, no-man's-land is hard to find nowadays, thus we need to buy it. Few significant states on the Caribbean islands are now safe-heavens for many rich of the world. However, we want to own an island to set our rules.
Depending on the place in the world where we buy the island (which depends on the success of the project and the funds raised), the way to get full autonomy is a matter of months.